1. Technical Field
The present invention relates generally to photonic integrated circuits having on-chip optical interconnects and, more specifically, to a photonic integrated circuit having a plurality of lenses and a method for making the same.
2. Introduction
The advancement of integrated circuit technology yields circuitry of increasingly smaller sizes with increased processing capabilities. However, conventional circuitry integrating copper lines with ultra-low K (ULK) dielectric materials experiences many problems as the copper lines are integrated with the ULK dielectric during back end of line (BEOL) semiconductor manufacturing. Many of these problems are attributed to the continued shrinkage of the copper line and the integration of the copper line with ULK materials. For example, as the copper lines shrink, current density of the copper line is increased, leaving such circuitry susceptible to electromigration of the copper line. Additionally, as the critical dimension of the copper line decreases with the shrinkage of the copper line, the copper/ULK integration becomes increasingly difficult to implement due to factors such as dielectric flop over, film cracking, and time dependent dielectric breakdown (TDDB).
One solution for addressing the shortcomings of copper/ULK integrated circuits is to replace the copper line formed during BEOL with a technology that provides on-chip integration of ultra-small circuits for manipulating light signals similar to the way electrical signals are manipulated in the chip. Such circuitry, known as photonic integrated circuitry or integrated optical circuitry, allows for the controlled manipulation (also referred to herein as “propagation”) of photons of incident light along a waveguide, thus providing on-chip ultra-dense integration. However, conventional photonic integrated circuitry is susceptible to noise and signal loss caused by a severe reduction in the propagation of the light along the waveguide. Therefore, there exists a need for photonic integrated circuitry that can improve light propagation along the waveguide while accommodating the demands of integrated circuitry advancement.